• 한국미생물·생명공학회지
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• 제11권3호
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• pp.205-210
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• 1983

유포자 유산균인 Lactobacillus sporogenes에 의한 extracellular $\beta$-galactosidase의 생산에 관한 연구에 이어 본 효소의 효소학적 일반성질을 조사하여 다음과 같은 결과를 얻었다. L. sporosenes $\beta$-glactosidase는 o-nitrophenyl-$\beta$-d-glaactopyranoside(ONPG)를 가수분해 할때에 0.05M-sodium phosphate buffer를 사용하여 pH6.8과 반응온도 6$0^{\circ}C$에서 가장 높은 효소활성을 나타냈으며 또한 이 효소반응의 activation enery는 50~6$0^{\circ}C$에서는 11,300ca1/mo1e, $50^{\circ}C$이하에서는 16,000ca1/mo1이었다. 효소활성에 미치는 금속 이온의 효과는 거의 없었으나 L-cysteine 10mM 첨가로 뚜렷한 첨가 효과를 나타내므로서 sulfhydryl enzyme의 특징을 보였다. 한편 lactose와 ONPG에 대한 Michaelis constant가 각각 6.45$\times$$10^{-2}$M, 1.48$\times$$10^{-3}$M을 나타냄으로서 본 효소는 ONPG에 휠씬 큰 친화성을 나타냈다. 또 ONPG분해반응은 lactose, galactose, glucose등의 당류첨가에 의해 그 반응속도가 현저히 감소되며 lactose는 특이하게 noncompe titive저해 양식을 나타내었으며 Ki값은 17.8mM galactose는 Ki값이 13.3mM, competitive inhibition glucose는 11.4mM의 Ki값에 uncompetitive inhibition을 나타냈다. 특히 본 효소는 중성부의 pH와 6$0^{\circ}C$에서 180분간 가열후에도 70%이상의 효소활성을 나타냄으로서 상당히 높은 열안정을 나타냄과 동시에 균체외 효소라는 장점도 아울러 가지고 있어 식품공업에의 그 이용 가능성이 매우 높다고 하겠다.

• 한국임상약학회지
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• 제15권1호
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• pp.55-60
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• 2005

The aim of this study is to investigate the effect of naringin on the pharmacokinetics of tamoxifen in rats. Tamoxifen (10 mg/kg) was administered orally 0.5 h and 3 days after oral administration of naringin (5 mg/kg). The plasma concentrations of tamoxifen were increased significantly tv naringin compared to control. Absorption rate constant ($K_a$) of tamoxifen with naringin was increased significantly compared to that of the control. The areas under the plasma concentration-time curve (AUC) and the peak concentrations ($C_{max}$) of tamoxifen with naringin were significantly higher than those of the control. Consequently, the relative bioavailability (R.B${\%}$) of tamoxifen with naringin was 2-3-fold higher than the control, and absolute bioavailability (A.B${\%}$) of tamoxifen were significantly higher (p<0.05 with coadministration, p<0.01 with pretreatment) than those of the control. The increased bioavailability of tamoxifen in rats with naringin might be associated with the inhibition by naringin of an efflux pump P-glycoprotein and the first-pass metabolizing enzyme CYP3A4.

• Journal of Plant Biology
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• 제39권2호
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• pp.107-112
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• 1996

To study the compensatory aspect of putrescine biosynthetic enzyme n tobacco suspension cultured cells, we examined the contents of the cellular polyamines and the activities of arginine decarboxylase (ADC, EC 4.1.1.19) and ornithine decarboxylase (ODC, EC 4.1.1.17) in the tobacco suspension cells treated with $\alpha$-difluoromethyl arginine (DFMA) or $\alpha$-difluoromethyl ornithine (DFMO). In the untreated cells, the content of the cellular putrescine was decreased during the first 3 hours and then subsequently increased. However, the content of the cellular spermidine and spermine remained constant during the incubation time. While ADC activity increased after 6 hours, ODC activity decreased following the rapid increase until 6 hours. DFMA induced the decrease in the contents of putrescine and spermidine, and the increase in that of spermine. It also caused the inhibition of ADC and ODC activities throughout the incubation time. DFMO produced the stimulation of ADC activity about 2 times of untreated cells and the decrease in the content of putrescine about 50% of them at 12 hour. The application of putrescine or cycloheximide prevented the increase of ADC activity by DFMO but that of actinomycin-D did not show any detectable effect. The stimulation of ADC activity by DFMO in tobacco suspension cultured cells was probably due to the enhancement of de novo synthesis for ADC protein, which might be regulated in the translation step by the content of the cellular putrescine.

• Journal of Pharmaceutical Investigation
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• 제34권1호
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• pp.15-21
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• 2004

The pharmacokinetics of orally administered verapamil (10 mg/kg) was studied in six rabbits after 20 min pretreatment with quercetin ad coadministration of quercetin (2.0 mg/kg, 1 mg/g and 20 mg/kg, respectively). Pretreatment with quercetin significantly (p < 0.01, p < 0.05) increased the plasma concentration of verapamil. However, coadministration of quercetin showed no significantly effect on the pharmacokinetic parameters of verapamil. The elimination rate constant $(K_{el})$ of verapamil pretreated with quercetin (1 mg/kg and 20 mg/kg) was significantly (p < 0.05) reduced compared with control. The area under the plasma concentration-time curve (AUC) and the peak concentration $(C_{max})$ of verapamil pretreated with quercetin (2.0 mg/kg, 10 mg/kg and 20 mg/kg) were increased significantly (p < 0.01, p < 0.05) compared with control. Pretreatment with quercetin (2.0 mg/kg, 10 mg/kg and 20 mg/kg) significantly (p < 0.01, p < 0.05) increased the relative bioavailability of verapamil to 159 - 219%. These results suggest that quercetin alters disposition of verapamil by inhibition of P-glycoprotein efflux pump and its first-pass metabolism. The dosage of verapamil should be adjusted when it is administered chronically with quercetin in a clinical situation.

• 한국식품위생안전성학회지
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• 제10권3호
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• pp.133-138
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• 1995

In vitro antimutagenic activity of methanol extract from brrwn rice and its physico-chemical characteristics were investigated using Salmonella typhimurium reversion assay and SOS chromotest. Methanol extracts of brown rice were not mutagenic compared with direct and indirect, mutagenicities of 4NQO (4-nitroquinoline oxide), 2NF(2-nitrofluorene), Trp-p-1(3-Amino-1,4-dimethyl-5H-pyrido-[4,3-b]indole), and Trp-p-2(3-Amino-1-methy-5H-pyrido-[4,3-b]indole). Antimutagenic activity against the indirect mutagenicties induced by Trp-p-1, Trp-p-2 and AFB1 (aflatoxin B1) was found in methanol extract. Even though antimutagenic activity showed dose-dependent, it remained constant at inhibition rate ranging 60~90% when the concentration was abov 3mg/plate in the S. typhimurium reversion assay and 0.2~0.6 mg/assay in the SOS chromotest. The antimutagenic activity of the methanol extracts was stable at various pH (2, 7 and 10), temperatures (60, 80 and 10$0^{\circ}C$)and heation times (2, 4, 6, 8, 10 min at 10$0^{\circ}C$).

• Journal of Pharmaceutical Investigation
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• 제36권3호
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• pp.157-160
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• 2006

This study investigated the effect of clarithromycin on the pharmacokinetics of ambroxol in rats. The pharmacokinetic parameters of ambroxol in rats were determined after the oral administration of ambroxol (12 mg/kg) in the presence or absence of clarithromycin (5 or 10 mg/kg). Compared with the control (given ambroxol alone), coadministration of clarithromycin significantly (p<0.05 at 5 mg/kg; p<0.01 at 10 mg/kg) increased the area under the plasma concentration-time curve (AUC), peak plasma concentrations $(C_{max})$ and absorption rate constant $(K_a)$ of ambroxol. Clarithromycin increased the AUC of ambroxol in a dose dependent manner within the dose range of 5 to 10 mg/kg. The absolute bioavailability (AB%) of ambroxol in the presence of clarithromycin was significantly higher than that of the control (p<0.05 at 5 mg/kg; p<0.01 at 10 mg/kg), and the relative bioavailability (RB%) of ambroxol with clarithromycin was increased by 1.32-to 1.71-fold. However, there were no significant changes in time to reach peak concentration $(T_{max})$ and terminal half-life $(T_{1/2})$ of ambroxol in the presence of clarithromycin. Coadministration of clarithromycin enhanced the bioavailability of ambroxol, which may be due to the inhibition of intestinal and hepatic metabolism of ambroxol by CYP 3A4. Further studies for the potential drug interaction are necessary since ambroxol is often administrated concomitantly with clarithromycin in humans.

• Journal of Microbiology and Biotechnology
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• 제17권7호
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• pp.1183-1190
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• 2007

A metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (TCS), was used to reduce excess sludge production in biological wastewater treatment processes. Batch experiments confirmed that 0.4 mg/l of TCS reduced the aerobic growth yield of activated sludge by over 60%. However, the growth yield remained virtually constant even at the increased concentrations of TCS when cultivations were carried out under the anoxic condition. Reduction of sludge production yield was confirmed in a laboratory-scale anoxic-oxic process operated for 6 months. However, it was found that ammonia oxidation efficiency was reduced by as much as 77% in the presence of 0.8 mg/l of TCS in the batch culture. Similar results were also obtained through batch inhibition tests with activated sludges and by bioluminescence assays using a recombinant Nitrosomonas europaea (pMJ217). Because of this inhibitory effect of TCS on nitrification, the TCS-fed continuous system failed to remove ammonia in the influent. When TCS feeding was stopped, the nitrification yield of the process was resumed. Therefore, it seems to be necessary to assess the nitrogen content of wastewater if TCS is used for reducing sludge generation.

• BMB Reports
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• 제28권1호
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• pp.83-86
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• 1995

In the course of screening for new aminopeptidase M inhibitors which were expected to be analgesic, immunopotentiating, or anti-metastatic agents, the novel synthetic substance MR-387C[(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoyl-L-valyl-L-prolyl-L-leucine] (M.W. 504 daltons) was obtained. It was competitive with the substrate and had an $IC_{50}$ value of $0.04\;{\mu}m/ml$ ($7.9{\times}10^{-8}\;M$) and an inhibition constant ($K_i$) of $3.8{\times}10^{-8}\;M$. This novel MR-387C was compared with various known inhibitors of aminopeptidase M. It inhibited the enzyme more strongly than any other microorganism-originated inhibitor, except probestin.

• 약학회지
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• 제44권3호
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• pp.245-250
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• 2000

Because nonsteroidal anti-inflammatory drugs are reported to cause fluid retention and hypertension by inhibition of prostaglandin synthesis, the effects of piroxicam on pharmacodynamics and pharmacokinetics of nifedipine were studied in male spontaneously hypertensive rats. They received nifedipine (0.5 mg/kg) alone or combined with piroxicam (5 mg/kg) intravenously. Plasma levels norepinephrine, an index of sympathetic stimulation, were measured prior to each treatment and 5 min after drug administration. Changes in blood pressure were examined serially and blood samples for analysis of nifedipine were also taken for 6 hr following drug administration. Plasma nifedipine concentration were assayed by HPLC and pharmacokinetic parameters were calculated. Blood pressure was reduced (p<0.01), but plasma norepinephrine level was increased (p<0.05) by nifedipine administration. Anti-hypertensive effect of nifedipine was potentiated (p<0.05) by piroxicam coadministration, but effect of nifedipine on plasma norepinephrine level was not affected. In case of rats received nifedipine and piroxicam, plasma nifedipine concentrations were higher (p<0.05) than those from rats received nifedipine alone at 2,3,4,5 and 6 hours following drug administration. The area under the plasma concentration vs. time curve was increased (p<0.05), while the elimination rate constant was decreased (p<0.01) by piroxicam coadministration. No significant differences were observed in the plasma clearance, apparent volume of distribution and elimination half-life. Thus, piroxicam not only potentiated antihypertensive effect of nifedipine, but also altered nifedipine pharmacokinetics in the rats. It is concluded that the potentiation of nifedipine antihypertensive effect might correlate with the increment of its plasma concentration by piroxicam coadministration.

• 한국분말재료학회지
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• 제13권2호
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• pp.129-137
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• 2006

In this study, high purity fine $BaTiO_3$ powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The $Al_{2}O_{3},\;TiO_{2}$ and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of $SiO_2$, the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives.